1. Field of the Invention
The subject adaptive video image resolution enhancement system (and the method incorporated thereby) is generally directed to a system for generating the additional image pixels necessary for increasing the resolution of the video image initially represented by a plurality of original image pixels. More specifically, the subject adaptive video image resolution enhancement system generates and assigns for insert at the proper locations adjacent the original image pixels a plurality of supplementary image pixel intensity levels. The subject system accomplishes this in a manner that optimally preserves image fidelity so that the detrimental effects typically accompanying image resolution enhancement, such as the introduction of abrupt discontinuities in otherwise smooth image edges, are significantly diminished.
The need for resolution enhancement of an image defined by a set of image pixels is present in many video applications. For instance, where an original image is expanded in size, either to simply zoom into a portion thereof, or to re-display it on a display monitor having a larger or denser array of available image pixels, the expanded image would invariably be characterized by discontinuous, jagged edges and a general degeneration of discernible details if a corresponding enhancement in its image pixel resolution is not also performed. Similarly, where a video image is to be electronically transmitted to remote site to support, for example, a video conferencing application, the goal towards instantaneous exchange of video information between conferencing sites demands that the volume of data transmitted be minimized as much as possible. Consequently, the video reproduced at the receiving site often lacks the image data content to yield high fidelity images. There is, therefore, a need exemplified in such applications for a system capable of generating additional pixel data with which to supplement some or all of the pixels of an original image in a manner which preserves much, if not all, of the fidelity present in the original image.
Simply adding additional image pixels in reproducing an original video image, or a portion thereof, does not necessarily meet this need. The additional image pixels must be carefully generated. One must consider in this regard that the features of a given video image which most perceptively affect its overall image fidelity are the numerous image edge portions by which that image is typically defined. Whether they be ones tracing the peripheral outlines of an image or ones tracing particular features within the body of the image, edges are highly discernible and therefore disproportionately important to the average viewer in visually discriminating the image. Thus, it is essential for the preservation of image fidelity that the smoothness and sharpness of edges be effectively preserved.
2. Prior Art
Video image resolution enhancement systems and image size expansion systems are known in the art. The best prior art known to Applicant includes U.S. Pat. Nos. 4,853,794; 5,418,899; 5,473,383; 5,054,100; 5,131,057; 5,515,457; 5,513,281; 5,125,042; 4,532,602; 5,444,493; 5,579,418; 4,833,531; 5,294,998; 5,301,266; 5,329,614; 5,450,096; 5,418,900; 5,627,953; 5,388,166; 5,418,714; and, 5,384,904. This prior art reveals that it is known in the prior art to perform various types of interpolation such as nearest neighbor, bilinear, and cubic convolution. The prior art also discloses systems or methods which perform edge detection for adjusting the interpolation process to incorporate such measures as compensation for blurring that might otherwise occur. The prior art, however, fails to disclose a system or method which provides the degree of adaptivity provided by the present invention, much less a system or method which effects such adaptivity by alternatively performing a bilinear interpolation scheme and an adaptive interpolation scheme responsive to a classification process as provided by the present invention.
Systems and methods known in the prior art which seek to offer image resolution enhancement with a level of adaptivity sufficient to measurably compensate for the detrimental effects on image fidelity of processes such as image scale expansion invariably fail to yield the combined degree of effectiveness and computational efficiency to be practicable. Consequently, the resolution enhancement systems most widely utilized in the prior art have been those systems which simply employ one known form of interpolation, such as bilinear interpolation, wherever possible in the entire field of a given image. While, in most cases, bilinear interpolation is acceptable for low-contrast, internal body portions of an image, it is not acceptable for more discernibly contrasted portions such as an image's edge portions. High image fidelity cannot be consistently preserved without additional measures.